Multiple circuit breaker



July 11, 1950 G. D. HANCHETT, JR

MULTIPLE CIRCUIT BREAKER Filed Dec. 6, 1947 W 1 Ema Em Sw Q R wsfi m m$5m mxvwmi 8 EEE 6% 3 T {mum llll lbw? him P a Q 1 1 1 1 1 1 .a Q r R Q WJ. DGPMMWDGD v M w l m u m vm mm m mm INVENTOR GEORG D. HANCHETT' uckATTORNEY Patented July 11, 1950 MULTIPLE CIRCUIT BREAKER George D.Hanchett, Jr., Millburn, N. J assignor to Radio Corporation of America,a corporation of Delaware Application December 6, 1947, Serial No.790,060

12 Claims.

The present invention relates to circuit breakers and, moreparticularly, to a circuit arrangement for providing overload protectionfor a plurality of separate circuits. All of the other heretofore knownmethods available for protecting radio transmitters and equipment ofwhich I am aware have certain disadvantages. Fuses are not very reliableand for high voltage proection are relatively expensive. Magneticcircuit breakers, while ordinarily superior to fuses, ore quiteexpensive when a number of circuits have to be protected. Furthermore, amagnetic circuit breaker is not easily reset. Circuit breakers of thistype are ordinarily equipped with a local directly acting operatinglever for resetting. The circuit breakers are either mounted directly ona radio transmitter panel itself or somewhere on the power supplychassis. Thus, when a breaker operates, it is necessary to leave theoperating position and go to the breaker to return the transmitter tothe air. In the event it is desired to arrange such circuit breakers forremote resetting, some form of magnetic resetting device is required butthis feature greatly increases the cost of the circuit breaker.

An object of the present invention, therefore, is to provide a multiplecircuit breaker which will overcome the foregoing difficulties.

Another object of the present invention is the provision of anarrangement for using electronic tubes to accomplish circuit protection.

Another object of the present invention is the provision of anelectronic circuit breaker which will protect several independentcircuits with the same breaker.

A further object of the present invention is the provision of anelectronic circuit breaker which may be reset by throwing a simpleswitch which may be located at any convenient location.

Sti l another object of the present invention is the provision of acircuit breaker as aforesaid which will immediately reoperate if thecircuit fault has not cleared.

Still a further object of the present invention is to provide a circuitbreaker which is fast enough in action to prevent damage to metersassociated with the circuits protected.

The foregoing objects and others which may appear from the followingdetailed description are attained by providing an electronic circuitbreaker using a number of Thyratrons or gas discharge tubes having acommon plate circuit including a circuit opening relay. The gasdischarge tubes are so arranged that .space currents of the .variousstages in the radio transmitter with which they are associated applypredetermined voltages to the control grids of the tubes. When thesevalues are exceeded, the gas discharge tubes are triggered into action.The resultant plate current flow through the common relay winding opensa circuit supplying plate potential to the transmitter. Due to thenature of a gas discharge tube, once the grid has been triggered, platecurrent continues to flow until the plate potential is reduced belowionization potential. The control circuit for reclosing the main circuitbreaker is so arranged that the operation of closing the main circuitbreaker removes plate potential from the gas discharge tubes.

An additional feature of the present invention is the arrangement ofsmall filamentary lamps in the individual plate circuits of the gasdischarge tubes adapted to become illuminated when the gas tubes drawcurrent. These small lamps thus act as pilot lights to indicate which ofthe various stages of the transmitter is causing the trouble.

While the present invention is described as being applied to a radiotransmitter, it may equally well be employed for circuit protection whena number of separate circuits are supplied with current from a singlesource and it may not be undesirable to disable all circuits uponfailure of any one individual circuit.

To insure fast action, the initial relay current may be increased byabout 50% through the use of a condenser charged by a resistance inseries with the source of anode potential for the gas tubes. Uponionization of the gas discharge tubes, the energy in the condenser isdischarged through the relay coil, causing increased speed of operationof the protective relay. After the initial charge has been dissipated,only normal relay current flows.

The present invention will be more fully understood by reference to thefollowing detailed description which is accompanied by a drawing havinga single figure. In this figure a radio transmitter T is indicated inblock diagram form as including, for example, an oscillator O, a bufferamplifier A, a modulator M and power amplifier PA, each of which is tobe separately monitored for excessive anode current. A high voltagesupply for the anode circuits of the various stages in transmitter T issupplied by high voltage power supply Ill. The filaments of the variousstages are preferably supplied from separate windings of a filamenttransformer [2. Thus winding l4 supplies filament current to theoscillator stage and windings l6, l8 and 20 supply filament current tothe bufier amplifier A, modulator M and power amplifier PA respectively.The primary 22 of the filament transformer is connected to the usual 110volt, 60 cycle power source through the filament control switch 24. Thefilament control switch also applies 110 volt, 60-cycleenergy to theprimary of a power transformer 30 having a high voltage winding 3|, arectifier filament winding 32 and a further filament winding 33. Thehigh voltage winding 3! and the filament winding 32 are connected torectifier tube 35 in a conventional full wave rectifier connection. flheresultant'direct current output is filtered by a series resistance 36and a filter condenser 31 having a bleeder resistor 38 thereacross.Thefiltereddirectacmrent is applied, through relay winding ,56 totheanodes of gas tubes 50, 52 and 54.

Now, the filament windings l6, I8 and 20 sup-- plying the transmitterstages A, -M-and PA each have mid-taps Which-would normallybedirectlyconnected to round or the negative side of-the high voltage supply-to-com plete the anode current circuit. In some casesbias resistors may be40, 42 and 44 are connected between thecenter =taps of windings l6,Iii-and 20 respectively and ground. These'resistors are large enough inresistance to produce -avoltage thereacross some- What in excess of twovolts-at-the minimum current desired for circuit breaker operation. Po-

tentiometer-s 45 connected across each of the resistors All, 42 and Mprovide for fineadjustment to the exact voltage-to be appliedto thegrids of -tubes 50, 52 and =54-for triggering ofi these tubes whenexcessive anode currents are drawn by the various-stages of thetransmitter. The moving -arm of eachofthepotentiometers tli is connected'to the control grid of one of the gas discharge pentodes 50,52 and' '4.In-the anode circuits of =each ofthese tubes is connected a:filamentlamp 55 serving as a pilot lightto indicate which gas tube isoperating, and :thus the stage of the transmitter which is in trouble.'The screen electrodes and cathodes of each of the tubes-5l,-'52 and 54are connected together and to the negative end ofresistor 38. "Thisterminalis connected to ground through the further resistor 51 ibypassedby condenser'58. "-Resistor 5l acts'as -a cathode 'bias resistor settingthe standing bias -on tubes 50, '52 and 54 simultaneously, which mustbeat 'least overcome by the-positive potentialapplied to their gridsfrom resistors 40, 42 and M. Now, when the voltage dropacross-any of theresistors 40, 42 and 4'4 exceedsthe predetermined negative gridpotential applied by resistor'51-the gridof corresponding tube 50,-=52,or 54 becomes=positive to such an extent that the tube becomesconductive. This causesa'fiow'ofcurrent from the rectifier 35throughthe-windi-mg-ofrelay' 56, causing relay 56 to separate itscontacts 60. This opens the circuitbetween-the LlO volt supplyand 'theinput terminals or the high voltage power supply It. Thelamp55associated with-theconductive gastube I also lights.

Inthe circuit between the power source and the input-terminals of ypowersupply It] iscon- 'nected -half of a=double pole single throw switch 62.The otherhalf orthe switch is connected in series between the winding ofrelay 56 and'the anodes of tubes 50, 52 and 54; Now toreenergize thetransmitter the operator opens switch 62 which removes the input to thehigh voltage power supply Ill and simultaneously opens the circuitbetween the rectifier and the gas discharge tubes 50, 52 and 54. Thiscauses the conductive one of these tubes to cease drawing anode current.Relay 55 drops back and closes its contacts 60. Reclosingthe platepowerz-switch 62 reapplies anode potential to the transmitter T. If thefault in the transmitter which causes the increase of voltage dropacross the resistors 80, Mandi-dis still present, the circuit breakerimmediately reopens.

The-use-ofa large filter capacitor 3? for the rectifier supply and thegas discharge tubes provides a reservoir of energy which increasesathevspeed -'of:,oper ation of relay 56. After the initial charge storedin condenser 3'! has been dissipated, however, only normal relay currentflows because it is limited by the resistance of resistor 3B and thepilotlamp55 in the energized gas discharge tube circuit. "It'has beenfound that the action of the circuitbreaker isfast enough in mostcases'so that the pointerof a meter connected in theplate supply of thetrans- -mitter will not reach "full scale deflection even on a deadshortcircuit.

'Since the electronic'circuit breaker is usually operated near strongradio'frequency fields, it is desirableto incorporate some radiofrequencyifilter in the grid circuit of each gasdischarge tube. Thisisprovided by a mica-capacitor l0 connected directly across tube socketconnectionsto the scribed from the viewpoint of protecting :threeseparate stages in a radio-transmitter, any additional number ofcircuits which it may beds- -sired to protect, may be protected bymerely adding-extra gas discharge tubes in circuits sim- -ilar tothoseshown-for 58,52 and 5t and connected to a resistor in-the circuitto be protected having a voltage drop thereacross which varies in thedesired sense. Furthermore, while the foregoing description hasbeenpredicated on the=use of the filamentary type tubes utilizing a centertapped filament winding on transformer 12, indirectly heated cathodetype tubesmay be used in the transmitter, the protective resistances, 42and 44 being placedin series between the cathode returns of the variousstages and a common ground connection. What is claimed is: :1. A circuitbreaker arrangement including a mumberof resistors one individual toeach of a number of circuits to'be protected, a gas-discharge tubeassociated with each of said resistors, said tubeseach having'acontrolelectrode and an anode,a connection from the control electrodeofeach of said "tubes'to its associated resistor and connections from saidanodes through a common winding of arelay to a source of potentialpsaid-relay having normally closed backcontacts connected betweenall of saidcircuits and another source of potential.

2. A circuit breaker arrangement including a number of resistors, oneindividualto each of a numberof circuits to be protected, a gasdischarge tube associated witheach of said-resistors said tubes eachhaving a control electrode and 'an anode, a connection from the controlelectrode of each of saidtubes 'to its associated resistor' andconnections fromTsaidanodesithrough. a common winding of a relay to asource of potential, said relay having normally closed back contactsconnected between all of said circuits and another source of potential,and means for disconnecting and reconnecting said source of anodepotential to reset said circuit breaker arrangement.

3. A circuit breaker arrangement including a number of resistors, oneindividual to each of a number of circuits to be protected, a gasdischarge tube associated with each of said resistors, said tubes eachhaving a control electrode and an anode, a connection from the controlelectrode of each of said tubes to its associated resistor so arrangedthat as the current through said resistor increases, said controlelectrode becomes positive, means for applying a standing negative biasto each of said control electrodes and connections from said anodesthrough a common winding of a relay to a source of potential, anindicator lamp in each of the last-mcntioned connections, said relayhaving normally closed back contacts connected between all of saidcircuits and another source of potential.

4. A circuit breaker arrangement including a number of resistors, oneindividual to each of a number of circuits to be protected, a gasdischarge tube associated with each of said resistors, said tubes eachhaving a control electrode and an anode, a connection from the controlelectrode of each of said tubes to its associated resistor to rendersaid control electrode positive as the current through said resistorincreases, means for applying a standing negative bias to each of saidcontrol electrodes and connections from said anodes through a commonwinding of a relay to a source of potential, an indicator lamp in eachof the last-mentioned connections, said relay having normally closedback contacts connected between all of said circuits and another sourceof potential, and means for discon-- necting and reconnecting saidsource of anode potential to reset said circuit breaker arrangement.

5. In a radio transmitter having a number of separate stages, aconnection from a power supply for said transmitter to each of saidstages, said connection including normally closed back contacts of arelay, individual resistors connected from each of said stages toground, a number of gas discharge tubes each having a control electrodeand an anode, a connection from each of said control electrodes to oneof said resistors, connections from all of said anodes through a windingof said relay to a source of potential, means for biasing said controlelectrodes to render said tubes inactive for normal current flow throughsaid resistors, said control electrode connections being arrangedwhereupon an increase in current through any of said resistors above apredetermined value will cause the associated gas tube to ignite, theanode current flowing through said relay winding acting to open saidnormally closed contacts.

6. In a radio transmitter having a number of separate stages, aconnection from a power supply for said transmitter to each of saidstages, said connection including normally closed back contacts of arelay, individual resistors connected from each of said stages toground, a number of gas discharge tubes each having a control electrodeand an anode, connections from each of said control electrodes to one ofsaid resistors, connections from all of said anodes through a winding ofsaid relay to a source of potential, means for so biasing said controlelectrodes to render'said tubes inactive for normal current flow throughsaid resistors, said control electrode connections being arrangedwhereupon an increase in current through any of said resistors above apredetermined value will cause the associated gas tube to ignite, theanode current flowing through said relay winding acting to open saidnormally closed contacts, and means for disconnecting and reconnectingsaid source of anode potential to extinguish said ignited gas tube.

7. In a radio transmitter having a number of separate stages, aconnection from a power supply for said transmitter to each of saidstages, said connection including normally closed back contacts of arelay, individual resistors connected from each of said stages toground, a number of gas discharge tubes each having a control electrodeand an anode, connections from each of said control electrodes to one ofsaid resistors, connections from all of said anodes through a Winding ofsaid relay to a source of potential, means for biasing said controlelectrodes to render said tubes inactive for normal current flow throughsaid resistors, said control electrode connections being arranged toignite any of said tubes upon an increase in current above apredetermined value through the associated resistor, the anode currentflowing through said relay winding acting to open said normally closedcontacts, and an indicator lamp in each of the connections from saidanodes to said relay winding.

8. In a radio transmitter having a number of separate stages, aconnection from a power supply for said transmitter to each of saidstages, said connection including normally closed back contacts of arelay, individual resistors connected from each of said stages toground, a number of gas discharge tubes each having a control electrodeand an anode, connections from each of said control electrodes to one ofsaid resistors, connections from all of said anodes through a winding ofsaid relay to a source of potential, means to bias said controlelectrodes to render said tubes inactive for normal current flow throughsaid resistors, said control electrode connections being arranged torender any one of said tubes active upon an increase in current above apredetermined value through the corresponding resistors, the anodecurrent flowing through said relay winding acting to open said normallyclosed contacts, means for simultaneously disconnecting and reconnectingsaid power supply and said source of potential to reinactivate saidactivated tubes and reactivate said transmitter, and an indicator lampin each of the connections from said anodes to said relay winding.

9. An arrangement for disconnecting a power supply from a plurality ofcircuits upon the current in any one of said circuits exceeding a valuepredetermined therefor, said arrangement including a plurality ofgaseous discharge tubes each having a cathode, a control electrode andan anode, a source of direct operating potential for said tubes, a relayhaving a winding connecting said source of direct operating potentialacross the anode-cathode path of all of said tubes and a normally closedcontact structure, contacts of said structure being interposed betweensaid power supply and all of said circuits, a resistive element in eachof said circuits responsive to said current flow therein, and means toconnect the resistive element in each of said circuits to the controlelectrode of a corresponding tube to render the same conductive upon thecurrent flowing in said resistor exceeding a predetermined valuetherefortoactuate said relay and open. said contacts to disconnect saidpower supply ,from .Said circuits.

10. An arrangement for disconnecting a power supply from a plurality ofcircuits upon the current in any one of saidcircuits exceeding a valuepredetermined therefor, said arrangement including a plurality ofgaseous discharge tubes each having a cathode, a control electrode andan anode, a source of direct operating potential for said tubes, a relayhaving a winding connecting said source of direct operating potentialacross the anode-cathode path of all of said tubes and a normally closedcontact structure,.contacts. of said; structure being interposed betweensaid power supply andall of said circuits, a resistive element in eachof said circuits responsive-tosaid current flow therein, means toconnectthe resistive element in each of saidcircuits to thecontrolelectrode of a corresponding tube to render the same conductive upon thecurrent flowing in said resistor exceeding a predetermined valuethereforto actuate said relay and open said contacts to disconnect said powersupply from said circuits,

and means connected to said relay windin to I provide aninitial surge ofrelatively, high current therethrough to increase the speed of operationof said relay.

11. Anarrangement, for disconnectinga power supply from a plurality ofcircuits upon thecurrent in any one of said circuits exceeding a valuepredetermined therefor, said arrangement includin a plurality of gaseousdischarge tubes each-havinga cathode, a control electrode and an anode,a source, of direct operating potentialflfor said tubes, a relay havinga winding connectin said source of direct operating potential across theanode-cathode path. of all of said tubes and a normally closedcontaetstructure, contacts of said structure being interposed betweensaid power supply and all of said circuits, a resistor in each of saidvcircuits responsive to said ourrent flow therein, means to connectthe'resistor in each of said circuits to the control electrode of acorresponding tube to render the same conductive upon the currentflowing in. saidresistor exceeding a predeterminedvalue therefor to ac-8 tuatesaidrelay and open said contacts to disconnect said power supplyfrom said circuits, and means interposed in the anode circuit of saidtubes to disconnect and reconnect said source of operating potential torender the conductive tube inactive toreset said arrangement.

12. An arrangement for disconnecting a power supply from a plurality ofcircuits upon the current in any one of said circuits exceeding a valuepredetermined therefor, said arrangement including a plurality ofgaseous discharge tubes each having a cathode, a control electrode andan anode, a source of direct operating potential for said tubes, a relayhaving a winding connecting said source of direct operating potentialacross the anode-cathode path of all of said tubes and a normally closedcontact structure, contacts. of said structure being interposed betweensaid power supply and all of said circuits, a resistor in each of saidcircuits responsive to said current flow therein, means to connect theresistor in each of said circuits to the control. electrode of acorresponding tube, means to bias said tubes to render the sameconductive only upon the current flowing. in the corresponding resistorexceeding a predetermined value therefor to actuate said relay and opensaid contacts to disconnect said power supply fromsaid circuits, and afilter circuit comprising a series resistor and a shunt capacitorconnected to said relay winding to provide an. initial surge ofrelatively high current therethrough to increase the speed of operationof said relay and thereafter to limit the current torthe normal value.

GEORGE D. HANCHETT, JR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,506,275 Stevenson Aug. 26, 19241,671,205 Oswald May 29, 1928 1,743,443 Fearing Jan. 14, 1930 2,064,192Brown Dec. 15, 1936 2,079,446 Goldsmith May 4, 1937

